The work outlined in this research project is directed toward the study of the process of neural excitation of hair-cell systems, especially in the cochlea. Experiments are planned to test and improve current theories of electromechanical transduction in the organ of Corti, and to ascertain the role of te cochlear microphonics (CM) and summating potentials (SP) in the excitatory processes of the VIIIth nerve fibers. This will be accomplished by simultaneously recording the cochlear potentials and the neural responses of single fibers before and during experimental modification of the cochlear potentials. Comparative studies will be made on the lateral-line system of the toad Xenopus laevis. The adequacy of the electromechanical hypothesis for the function of the hair cells in the lateral line will be tested by studying the effect of electrical polarization on the neural responses elicited spontaneously and by mechanical stimulation. BIBLIOGRAPHIC REFERENCES: D. Strelioff, S. T. Sitko and V. Honrubia: Role of inner and outer hair cells in neural excitation. Trans. Amer. Acad. Ophthalmol. Otolaryngol. 82: 322, 1976. S.T. Sitko, D. Strelioff and V. Honrubia: Source and maintenance of the endocochlear potential. Trans. Amer. Acad. Ophthalmol. Otolaryngol. 82: 35, 1976.